A single electron transistor (SET) uses controlled electron tunneling to amplify current, and includes a conductive island connected through two tunneling junctions to drain and source regions. The island is further connected to a gate electrode through a capacitor. Each tunnel junction includes a thin insulator (also referred to herein as a “tunnel barrier”) located between a source/drain region and the conductive island. When there is sufficient bias between source and drain regions, electrons can actively tunnel to and from the island through the tunneling junctions. The electric charge that flows through the tunneling junctions flows in multiples of the charge of a single electron (e).
SETs are being researched as a potential device option beyond the conventional complementary metal oxide semiconductor (CMOS) transistors. An SET can be useful when applied in, for example, a highly sensitive electrometer, single-electron spectroscopy, a charge sensor, an infrared radiation detector, a thermometer, a memory and microwave detection. SET characteristics depend on the tunnel barrier and uniformity of SET island size.